Method for operating a longitudinally guiding driver assistance system of a motor vehicle and motor vehicle

ABSTRACT

A method for operating a longitudinally guiding driver assistance system of a motor vehicle, especially of an ACC system, which is designed to control the speed of a motor vehicle to a desired speed in a free travel mode and/or keeps a controlled distance to a vehicle in front as the control object in a follow mode, at least one control parameter influencing control being adapted depending on at least one item of traffic information that describes traffic conditions on the currently traveled route, especially in the further course of the route, information is received from an external transmitter.

The invention relates to a method for operating a longitudinally guidingdriver assistance system of a motor vehicle, in particular an ACCsystem, which is configured for controlling the speed of a motor vehicleto a desired speed in a free travel mode and/or for controlling thespeed of the motor vehicle for maintaining a controlled distancerelative to a vehicle driving ahead as the control object. The inventionalso relates to a motor vehicle with such a driver assistance system.

Longitudinally guiding driver assistance systems for motor vehicles,which mostly automatically control the speed of the motor vehicle arealready known in many configurations. The simplest configuration of sucha longitudinally guiding driver assistance system is often referred toas speed control system (GRA) or cruise control. The speed of the motorvehicle is controlled to a speed that can be selected by the driver.These systems were enhanced, in particular under the name ACC system(Adaptive Cruise Control), by including a follow mode, which involvescontrolling to a fixed or driver-selectable control distance to thevehicle driving ahead as control object when the desired speed cannot beestablished due to a vehicle driving ahead, wherein often a defined timegap is used.

It is also known in so called pre-crash or emergency brake systems tocarry out longitudinally guiding interventions in order to avoid acollision with an object and/or to mitigate consequences of a collision.Such emergency brake systems are safety systems, which use environmentalsensors in order to determine the likelihood of a collision and when oneor multiple threshold values are exceeded to carry out various measures,in particular braking interventions. Further measures include warningthe driver, pre-conditioning of vehicle systems, in particular of thebrake system, the seat belt system, the airbags and the like.

In the longitudinally guiding driver assistance systems known today, inparticular also ACC or pre-crash systems with environmental sensorsystem, the reaction to events occurring in the area ahead are alwaysthe same. Mostly, an object in particular a control object is selected,based on which an intervention is performed in the motor vehicle.Disadvantageously, regarding the intervention it is thus notdistinguished in which situation, in particular which in trafficsituation, the vehicle is currently involved, which makes it difficultfor the customer to understand the action of the driver assistancesystem, which appears improvable with regard to safety.

The invention is therefore based on the object to set forth a method foroperating a driver assistance system, which is also responsive tospecial situations and traffic conditions.

For solving this object in a method of the aforementioned type it isprovided according to the invention that at least one control parameterwhich influences the control is adjusted in dependence on at least oneitem of traffic information which is obtained by an external sender andwhich describes the traffic conditions on the actually driven on road,in particular along the future course of the road.

According to the invention it is proposed to use an externally receiveditem of traffic information for example an item of traffic informationwhich describes a traffic jam ahead and/or a dangerous situation aheadand/or the status of a traffic light ahead in order to re-parameterizethe driver assistance system, in particular an ACC system, and/or anemergency brake system so that the driver assistance system is preparedfor imminent traffic changes. For example when a traffic jam and/or adangerous situation is reported, the driver assistance system can beprepared for the traffic jam because—in particular with regard to an ACCsystem—a fast deceleration may soon be expected.

The method according to the invention thus allows a situation-specificinfluence of a driver assistance system, in particular an ACC systemand/or an emergency brake system, based on external items of trafficinformation in particular those received by radio, in particular trafficdata or danger warnings so that the function can be optimized for thespecial situation. The behavior of the driver assistance systemcorresponds better to the expectations of the driver and a betterreaction in dangerous situations is possible in particular also anincrease of the safety of the driver assistance system.

It can concretely be provided that the item of traffic information isreceived by means of a communication device, in particular a radioreceiver from the stationary and/or moving sender. This means that thepresent invention uses systems for receiving external trafficinformation currently summarized under “Car2X”-systems in which motorvehicles can exchange items of information with each other as well aswith stationary communication devices using corresponding communicationdevices, wherein particularly advantageously a server is used as sender,which provides the traffic information to multiple motor vehicles.Expediently, the traffic information can be determined from, possibleyprocessed, sensor data received by at least one further motor vehicle.This means, the server which eventually sends the traffic informationcollects data, in particular sensor data, from a multitude of motorvehicles on different roads and analyzes these data road-section-specifically in order to obtain useful traffic information for motorvehicles which for example can also be used in navigation systems inorder to avoid traffic jams or the like. The road network is thusdivided into different road sections which are each assigned at leastone item of traffic information, which for example describes whether atraffic jam is present at this location, whether a dangerous situationis present or the like. Of course, an item of traffic information canalso relate to a concrete location for example when it reflects theactual state of a traffic light, which can also act as a sender. It isnoted that in particular a server that acts as a sender and containstraffic information relating to a traffic jam or dangerous situation,may not only determine these data from data of other motor vehicles butitems of traffic information may for example also be obtained from theinternet or from a local service for example a traffic monitoringsystem.

In a concrete embodiment of the present invention it can be providedthat when an item of traffic information indicates a traffic jam aheadand/or a dangerous situation ahead, the penetration depth can bereduced, in particular to zero, when approaching a vehicle driving aheadand/or a maximal possible acceleration is reduced and/or a maximalpossible deceleration is reduced and/or a merging-recognition forrecognizing fast lane changes is re-parameterized, wherein in particulara plausibilization threshold is reduced and/or a control distance to thevehicle driving ahead is increased.

As already described, the driver assistance system, in particular anACC-system, can be prepared for a traffic jam, thus the penetrationdepth can be reduced when approaching a vehicle driving ahead, forexample also to a value of zero, slightly reducing comfort but enablinga faster reaction. The maximal acceleration with which to follow avehicle driving ahead can also be reduced because in case of a trafficjam it can be assumed that if the vehicle ahead accelerates it will doso only for a short period of time. It is therefore also conceivablethat a maximal deceleration is reduced so that a slower approach occurs.It is also possible that the merging-recognition can be re-parameterizedbecause ahead of a traffic jam or in traffic jams other vehicles oftenchange lanes. Thus the plausibilization threshold can be lowered, i.e.,an individual that changes lanes can already become plausible as controlobject at a lower probability. It is further conceivable to increase thecontrol distance to the vehicle driving ahead since the latter isexpected to strongly brake when driving close to the traffic jam. Thusthe driver assistance system adjusts to the traffic conditions and canadjust its function so that it offers the best driving behavior inparticular with regard to safety.

In a further possible concrete embodiment of the method according to theinvention it can be provided that when an emergency brake system isprovided as driver assistance system and in case of an item of trafficinformation which indicates a dangerous situation ahead, in particular aperson and/or an animal and/or an object on the road, that theclassification threshold of standing objects which cannot be driven overis lowered and/or an intervention time point and/or a warning time pointis shifted to an earlier time point. In an emergency brake system, theparameterizing can also be changed in case of an impending danger due tofor example game, pedestrians or objects on the road or in case of atraffic jam. Thus the classification thresholds of standing objects,which cannot be driven over, can be lowered in order to enable a safereaction or to enable a reaction in the first place, to standingobjects. Intervention time points can also be moved forward in order toenable an earlier warning and intervention of the functions to imminentdangers and thus a better manageability of the critical situation.

In a further advantageous concrete embodiment of the present inventionit can be provided that in case of an item of traffic information whichindicates a red traffic light ahead, a plausibilization threshold forstanding objects is lowered and/or the manner of approaching is adjustedto control parameters that describe standing objects, in particular withregard to a slow and/or more comfortable approach. Thus the item ofinformation that standing objects are expected can advantageously beused in order to perform an appropriate re-parameterizing of the driverassistance system. It can further be provided to use knowledge about ared phase in order to influence the manner in which to approach standing(or very slow driving) objects, in particular also motor vehicles thatwait in front of the traffic light. The gap thus is not to be closedparticularly fast as is for example often desired in the case of ACCsystems, but a longer time can be used so that in case of a longer redphase a comfortable closing of the gap is possible.

Beside the method, the invention also relates to a motor vehicleincluding a longitudinally guiding driver assistance system with acontrol device, which is configured for carrying out the methodaccording to the invention. Thus, the motor vehicle can also have acommunication device for receiving externally provided trafficinformation. All embodiments relating to the method according to theinvention are analogously applicable to the motor vehicle according tothe invention so that the advantages of the invention can also beattained with the motor vehicle according to the invention.

Further advantages and details of the present invention become apparentfrom exemplary embodiments described in the following and by way of thedrawing. It is shown in:

FIG. 1 a schematic diagram of a motor vehicle according to the inventionand

FIG. 2 a flow chart of the method according to the invention.

FIG. 1 shows a schematic diagram of a motor vehicle 1 according to theinvention. In the present case it has an ACC system 2 with a controldevice 3, which is configured for carrying out an embodiment of themethod according to the invention. The motor vehicle 1 also has anemergency brake system 4 which also includes a control device 5, whichcarries out another embodiment of the method according to the invention.

Both control devices are connected with other vehicle systems, inparticular via a CAN-bus, in particular with environmental sensors fromwhich the data required for the function are obtained and with systemsto be controlled, in particular a brake system and/or a motor. The othervehicle systems also include a communication device 6 which can forexample be integrated into a radio of the motor vehicle 1. Via thecommunication device 6 data of an external stationary sender 7 can bereceived which is part of a server 8. On one hand, the server 8 receivesdata of different motor vehicles, in particular in the case when themotor vehicle 1 is also configured for sending data, also data of themotor vehicle 1, wherein these are mostly already processed sensor data.On the other hand, the server 8 also has access to further sources ofinformation such as the internet or a local service. From all theseitems of information the server determines a site-specific and/or roadsection-specific item of traffic information, which in the present caseindicates whether a traffic jam exists and/or a dangerous situationexists. In the present case, a further sender 9 is installed in atraffic light, wherein the sender 9 sends, i.e., broadcasts the actualstate of the traffic light 10 as item of traffic information to thesurrounding road users.

The respective control devices 3 and 5 now contain the trafficinformation provided by the communication device 6 and analyze the samein order to as the case may be allow a re-parameterization of the driverassistance systems 2, 4.

FIG. 2 shows as an overview the function of the method according to theinvention. In a step 11, the actual item of traffic information isreceived by the communication device 6 and forwarded to the controldevices 3 and 5. In a step 12, the actual item of traffic information isthen analyzed by the control devices 3 and 5, wherein it is for exampledecided based on distances, or in case the traffic information is givenon a scale, based on threshold values, whether control parameters of thedriver assistance systems 2, 4 should be adjusted. When this is the casethis adjustment occurs in a step 13. The method is then repeatedwhenever an actual item of traffic information can be received.

In the present case, when a traffic jam or a dangerous situation isahead, i.e., in particular displayed on the road section on which themotor vehicle 1 is located, the penetration depth for the ACC-system 2is reduced to zero when approaching a vehicle driving ahead, a maximalpossible acceleration and a maximal possible deceleration are reducedand a merging-recognition is re-parameterized for recognizing fast lanechanges in that a plausibilization threshold is lowered.

In the emergency brake system 4 the parameterizing is also changed incase of an impending danger due to game, pedestrians or objects on theroad, in that classification thresholds of standing objects which cannotbe driven over are lowered and intervention time points and warning timepoints are moved forward. In both systems, any time a red traffic lightis indicated ahead within a defined range, the recognition of standingobjects is accelerated in particular also in that plausibilizationthresholds or the like are lowered. When a red phase of a traffic lightis indicated, parameters that describe the approach-characteristics ofthe ACC system are adjusted so that the closing of the gap to standingobjects (waiting vehicles) occurs slower and more comfortable since thepossibility is given to “take time” at longer red phase.

Of course other adjustments of parameters for different trafficsituations are conceivable to which the method according to theinvention can be applied in order to optimize the function to thespecific traffic situation.

1.-9. (canceled)
 10. A method for operating a longitudinally guidingdriver assistance system of a motor vehicle configured in at least oneof two ways, a first way in which the longitudinally guiding driverassistance system is operated in a free travel mode to control a speedof the motor vehicle to a desired speed, a second way in which thelongitudinally guiding driver assistance system is operated in a followmode to control a speed of the motor vehicle to maintain a controldistance to a vehicle driving ahead as control object, said methodcomprising: adjusting at least one control parameter as a function of atraffic information received from an external sender and describing acurrent traffic condition on a road the motor vehicle drives on; andwhen the traffic information indicates the presence of a traffic jamahead or a dangerous situation ahead, adjusting the at least one controlparameter in at least one of four ways, a first way in which apenetration depth is reduced in relation to an approaching vehicledriving ahead, a second way in which a maximal possible speed islowered, a third way in which a maximal possible deceleration islowered, a fourth way in which a merging-recognition for recognizingfast lane changes is re-prarameterized by lowering a plausibilizationthreshold so as to render a lane change as control object more plausibleat a lower likelihood.
 11. The method of claim 10, wherein thelongitudinally guiding driver assistance system is constructed asACC-system.
 12. The method of claim 10, wherein the sender is stationaryor mobile, with the traffic information being received by the sender viacommunication device.
 13. The method of claim 12, wherein the sender isa radio receiver.
 14. The method of claim 12, wherein the sender isconstructed as a server.
 15. The method of claim 14, wherein the trafficinformation on the server is determined as a function of sensor datareceived by at least one further motor vehicle, said sensor dataoptionally being processed.
 16. The method of claim 10, wherein thetraffic information indicates a traffic jam ahead, a dangerous situationahead, or a status of a traffic light ahead.
 17. The method of claim 10,wherein the driver assistance system is constructed as an emergencybrake system, wherein, when the traffic information indicates adangerous situation ahead, the at least one control parameter isadjusted so that classification thresholds of standing objects whichcannot be driven over are lowered and/or an intervention time pointand/or warning time point is moved to an earlier time point.
 18. Themethod of claim 17, wherein the dangerous situation includes at leastone of a person, an animal and an object on the road.
 19. The method ofclaim 10, wherein when the traffic information indicates a red trafficlight ahead a plausibilization threshold for a standing object islowered or a control parameter which describes anapproach-characteristic of the driver assistance system to standingobjects is adjusted, in particular with regard to a slower and/or morecomfortable approach.
 20. The method of claim 10, wherein when thetraffic information indicates a traffic jam ahead or a dangeroussituation ahead the at least one control parameter is adjusted so as tolower the control distance to the vehicle driving ahead.
 21. A motorvehicle, comprising: a longitudinally guiding driver assistance systemconfigured in at least one of two ways, a first way in which thelongitudinally guiding driver assistance system is operated in a freetravel mode to control a speed of the motor vehicle to a desired speed,a second way in which the longitudinally guiding driver assistancesystem is operated in a follow mode to control a speed of the motorvehicle to maintain a control distance to a vehicle driving ahead ascontrol object; and a control device configured to operate thelongitudinally guiding driver assistance system, said control devicebeing configured to adjust at least one control parameter as a functionof a traffic information received from an external sender and describinga current traffic condition on a road the motor vehicle drives on; andwhen the traffic information indicates the presence of a traffic jamahead or a dangerous situation ahead, to adjust the at least one controlparameter in at least one of four ways, a first way in which apenetration depth is reduced in relation to an approaching vehicledriving ahead, a second way in which a maximal possible speed islowered, a third way in which a maximal possible deceleration islowered, a fourth way in which a merging-recognition for recognizingfast lane changes is re-prarameterized by lowering a plausibilizationthreshold so as to render a lane change as control object more plausibleat a lower likelihood.
 22. The motor vehicle of claim 21, wherein thelongitudinally guiding driver assistance system is constructed asACC-system.
 23. The motor vehicle of claim 21, wherein the sender isstationary or mobile, with the traffic information being received by thesender via communication device.
 24. The motor vehicle of claim 23,wherein the sender is a radio receiver.
 25. The motor vehicle of claim23, wherein the sender is constructed as a server.
 26. The motor vehicleof claim 25, wherein the traffic information on the server is determinedas a function of sensor data received by at least one further motorvehicle, said sensor data optionally being processed.
 27. The motorvehicle of claim 21, wherein the traffic information indicates a trafficjam ahead, a dangerous situation ahead, or a status of a traffic lightahead.
 28. The motor vehicle of claim 21, wherein the longitudinallyguiding driver assistance system is constructed as an emergency brakesystem, and wherein, when the traffic information indicates a dangeroussituation ahead, the at least one control parameter is adjusted so thatclassification thresholds of standing objects which cannot be drivenover are lowered and/or an intervention time point and/or warning timepoint is moved to an earlier time point.
 29. The motor vehicle of claim28, wherein the dangerous situation includes at least one of a person,an animal and an object on the road.